Timers and Better Interactions

You can now let go of the block.
The interaction class beefed up, you can now stop interactions if you
want.
Fixed a door bug, it closes with a floor now.
Added a simple follow camera.
Added a continuous mode to pressure plates, causing instant
deactivation.
Added timers to anything that'll reset. 10 seconds, naturally.
Added a SpriteSheet class as well.